Know your data 26: Confidence in numbers dropping

Now that you clicked on that, I'm here to tell you confidence - in - numbers dropping is not the same as confidence in numbers - dropping.

That's my reaction when I went to the Covid Tracking Project looking for California's testing numbers. Here's what I found:

Did someone explain what happened on Wednesday? The total number of test results jumped by 50% in one day, with most of those being negatives. The proportion of positive results went down from 11% to 7.5% in one day.

This type of weirdness makes data analysts nervous. It's hard to trust the data, and it destroys any ability to analyze trends.